The superior vena cava carries blood from the head, arms and upper torso to the heart. This thin-walled vessel is easily compressed by tumors or other pathology in the mediastinum leading to impedance in venous return. If the occlusion occurs gradually, collaterals may form thereby mitigating the symptoms. Airway compromise results from both direct compression of the tracheobronchial tree and edema of these airways due to venous engorgement.

SVCS/SMS is not typically considered to be a true medical emergency unless airway compromise or neurologic symptoms are present (Yellin et al. 1990). However, tumors with rapid growth can lead to a rapid progression of symptoms. Management consists of both relief of the obstructive symptoms and treatment of the underlying malignancy (Table 4.1). Most data regarding management of SVCS come from case series as there have not been many randomized controlled trials; such studies comparing management options for patients with SVCS/SMS have had difficulty accruing patients (Wilson et al. 2007b). Elevation of the head of the bed can assist in venous drainage and decreasing edema (Cheng 2009). All IV lines should be placed in the lower extremities, so as to prevent further raised hydrostatic pressure in the SVC. Loop diuretics are sometimes used, although it is unclear whether these agents have a significant effect on the rate of clinical improvement (Schraufnagel et al. 1981). In patients with SVC obstruction resulting from intravascular thrombosis associated with an indwelling catheter, removal of the catheter should be strongly considered.

Sedation should be avoided as much as possible, as sedative medications result in reduced respiratory drive and relaxation of bronchial muscles. When a biopsy is required, obtaining tissue under local anesthesia should be the goal. The indicators of risk for general anesthesia in such patients are controversial. Large retrospective reviews have not identified any single clinical sign or test that can accurately predict which patients with a mediastinal mass will experience complications under general anesthesia (Hack et al. 2008). Patients with stridor, orthopnea, wheezing, SVC obstruction, CNS symptoms, pericardial effusion, tracheal or bronchial compression >50–70 %, pulmonary artery outflow obstruction, or peak expiratory flow rate (PEFR) of <50 % are considered to be at higher anesthetic risk (Hack et al. 2008). Others have suggested that PEFR and tracheal cross-sectional area seem to be the most reliable criteria in identifying children at greatest risk for anesthetic complications, and that if both the PEFR and the tracheal cross-sectional area are >50 % of predicted values general anesthesia can be administered safely (Ricketts 2001). If general anesthesia is considered necessary, spontaneous ventilation should be maintained if possible.

As lymphoma and leukemia are among the most common causes of a mediastinal mass and resultant SVCS in children, many centers recommend delaying diagnostic biopsy in symptomatic patients for 24–48 h while emergent corticosteroids or radiation are given in an effort to shrink the tumor size. However, there is concern that such pretreatment can distort cellular morphology and thereby adversely affect the ability to make a histologic diagnosis (Ferrari and Bedford 1990). Retrospective reviews have found that pre-biopsy steroid or radiation treatment caused delay or failure of definitive diagnosis or staging in a minority of children; fortunately many of these patients who were empirically treated did well and have remained disease-free at last follow-up (Loeffler et al. 1986; Borenstein et al. 2000). In an effort to preserve tumor histology for diagnostic purposes, radiation oncologists should attempt to spare radiation to a limited portion of the tumor, with the later goal of obtaining untreated biopsy tissue from that region. This limited “postage stamp” approach to the radiation field is also used to safely treat various types of tumors (Slotman et al. 1996; Hayakawa et al. 1999). Alternate tissue sources from which to make the diagnosis should be considered when possible, including pleural or pericardial effusions and enlarged palpable lymph nodes (see Sect. 4.2.2.3). Ultimately, the decision to treat such a patient prior to obtaining tissue for biopsy should depend on the patient’s clinical status and severity of cardiorespiratory symptoms.

The pericardium is composed of a serous layer of mesothelial cells adherent to the surface of the heart and a fibrous parietal layer formed by the pericardium and reflecting back on itself. The space between these two layers contains up to 50 mL of fluid which serves as a lubricant. Excess fluid can accumulate in this space without affecting the pericardial pressure until it reaches the volume that begins to distend the pericardium, termed the pericardial reserve volume. Once this reserve volume is reached, pressure begins to rise sharply due to the relative inextensibility of the pericardium. The heart is then forced to compete with the increased pericardial contents for the fixed intrapericardial volume which in turn leads to an impaired filling of the cardiac chambers and hemodynamic compromise. This compression of the heart due to the pericardial accumulation of fluid is termed cardiac tamponade and can be life threatening (Spodick 2003).

The timing and type of treatment for pericardial effusion depend on the severity of symptoms (Table 4.1). If the effusion is asymptomatic, continued close observation for hemodynamic complications is required but the effusion generally resolves with treatment of the underlying malignancy (Bashir et al. 2007). In the case of tamponade or if the pericardial effusion is otherwise hemodynamically significant, the fluid should be drained emergently. Pericardiocentesis under echocardiographic guidance is the therapy of choice and has been shown to be a safe and effective treatment for pediatric oncology patients with symptomatic pericardial effusion or tamponade (Medary et al. 1996). In addition to relieving symptoms related to the effusion, this procedure can be used to determine the etiology of a malignant effusion. As the recurrence rate of pericardial effusions after initial drainage can be as high as 50 %, consideration should be given to introducing an indwelling pigtail drainage catheter at the time of pericardiocentesis to allow for prolonged drainage (Tsang et al. 1999). Surgical management of malignant pericardial effusion should be reserved for the rare case that cannot be controlled by this method (Maher et al. 1996). In the case of acute cardiac tamponade, the patient should receive volume resuscitation to elevate intracardiac pressures to greater than pericardial pressures. Mechanical ventilation with positive airway pressure should be avoided in these patients because it can further decrease cardiac output (Spodick 2003).

The pleural space is bordered by the parietal pleura which covers the inner surface of the thoracic cavity and the visceral pleura which covers the lung surfaces. Like the pericardial space, there is normally a small amount of lubricating fluid between these two layers, but this fluid can increase secondary to underlying pathology. Pleural effusions are classified as either transudates or exudates. Exudates are typically of infectious etiology and result from inflammation on the pleural surface. Transudates, on the other hand, are generally of noninfectious etiology and result from an imbalance between the rate of pleural fluid formation and its reabsorption as the distribution of hydrostatic and oncotic pressure across the pleura is altered.